In laser machining, a laser beam generation device is used in conjunction with an optical system to direct the laser beam onto a workpiece that is to be machined. The impingement of the laser beam on the workpiece locally melts and/or vaporizes the workpiece material to produce or extend a hole or cut in the workpiece. The location of the laser beam impingement point on the workpiece may be controlled by moving one or both of the laser beam and the workpiece relative to one another to thereby control the geometry of the hole or cut.
Laser machining of workpieces often produce edges along the cut features that exhibit taper. One approach to avoid tapered edges is to use a special trepanning head to rotate the laser beam at a spot location with a fixed tilt angle. The part remains stationary. Such an approach is only good for small hole drilling. Another approach is to rotate the part physically while keeping the laser beam at the same incident angle, which need high precision CNC stage (usually 4-5 axis) and sophisticated control software to achieve a zero taper cut.
There is a need for laser machining systems and methods using laser beams having uniform beam profile and narrow beam divergence for forming zero and negative taper machined cuts.